1. Field of the Disclosure
This disclosure pertains, in general, to semiconductor processing and, more specifically, to forming an integrated circuit device with contact openings.
2. Description of the Related Art
Interconnect technology is a factor in the ability to reduce the area of integrated circuit devices. Multi-level metallization layouts have assisted dimension shrinkage by having multiple metal lines share the same area of the device. In a multi-level metallization layout, a dielectric layer, termed an interlevel dielectric layer (“ILD”) or a pre-metal dielectric (“PMD”) layer, is formed between the first metal layer and the transistors. Typically, the dielectric layer is formed to isolate the metal layer from the transistors. To electrically connect the underlying gates of the transistors or the substrate (i.e. the source or drain region) to the first metal line, a contact opening is etched through the ILD layer and filled with a conductive material to form a conductive plug. Typically, a contact opening is formed between two transistors. These contact openings are desirably small so the transistors may be close together, but must also be reliable.
In one example, a PMD process leaves a void when depositing between two closely spaced gate electrode structures. Neighboring contact openings are formed in a PMD layer exposing a source/drain region within each opening. A void undesirably extends between the two neighboring contact openings along the two closely spaced gate electrode structures. An insulating liner layer can be deposited within the neighboring contact openings. The insulating layer constricts the void at the contact opening. The insulating layer can subsequently be anisotropically etched to allow electrical contact to be made to the source/drain region. However, exposing the source/drain region more than once during a contact opening formation sequence can negatively affect the resistivity of the source/drain region. There, thus, is a need for contacts that are reliable and allow for transistors to be close together that overcomes these problems.
Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the invention. The use of the same reference symbols in different drawings indicates similar or identical items.